drm/amd/display: skip disable CRTC in seemless bootup case

Resync FIFO is a workaround to write the same value to
DENTIST_DISPCLK_CNTL register after programming OTG_PIXEL_RATE_DIV
register, in case seemless boot, there is no OTG_PIXEL_RATE_DIV register
update, so skip CRTC disable when resync FIFO to avoid random FIFO error
and garbage.

Reviewed-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Signed-off-by: Fudongwang <Fudong.Wang@amd.com>
Signed-off-by: Rodrigo Siqueira <rodrigo.siqueira@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>